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United States Patent |
5,314,007
|
Christenson
|
May 24, 1994
|
Air cooler for LPG vehicles
Abstract
The combination of a converter in which liquid petroleum gas is changed in
phase from liquid to gas preparatory to fueling an internal combustion
engine by adding heat from a fluid, a dual three-way valve, an air-fluid
heat exchanger in a human-occupied compartment (the cab), and a fluid
circulation system independent of the internal combustion engine cooling
system. The dual three-way valve's position either directs engine coolant
tapped from the engine through the converter and air-fluid heat exchanger,
partially cooling the cab, or directs fluid from the independent fluid
circulation system through the converter and air-fluid heat exchanger,
fully cooling the cab. As an alternate embodiment for installations when
engine coolant can become temporarily too hot to exit the inverter below
ambient cab temperature, an independent bypass may be incorporated.
Inventors:
|
Christenson; Gary M. (1924 Continental St., Costa Mesa, CA 92627)
|
Appl. No.:
|
115758 |
Filed:
|
September 3, 1993 |
Current U.S. Class: |
165/43; 62/7; 123/557; 165/41 |
Intern'l Class: |
B60H 001/32; F25D 007/00 |
Field of Search: |
165/41,43
62/7
123/557
|
References Cited
U.S. Patent Documents
2028069 | Jan., 1936 | Horton | 62/7.
|
2183452 | Dec., 1939 | Gibbs et al. | 62/7.
|
2224740 | Dec., 1940 | Melcher | 62/7.
|
Foreign Patent Documents |
2158183 | May., 1973 | DE | 62/7.
|
Primary Examiner: Davis, Jr.; Albert W.
Attorney, Agent or Firm: Thackrey; James D.
Claims
I claim:
1. In apparatus having both a liquid petroleum gas internal combustion
engine cooled by circulating liquid through a heat exchanger and a
human-occupied compartment, a system for providing cooling to the
compartment from the heat of vaporization of the liquid petroleum fuel
being used, comprising the combination of:
an air-fluid heat exchanger in the human-occupied compartment, and
a converter in which liquid petroleum gas is expanded to the vapor phase
and heated to above the ambient atmospheric dew point by fluid on its way
to said air-fluid heat exchanger prior to being ducted to the internal
combustion engine, the cooled fluid emerging from said converter being
connected to said air-fluid heat exchanger inlet port, and
a centrifugal pump moving the fluid from the outlet port of said air-fluid
heat exchanger to said converter through a dual three-way valve discussed
below, and
an air-separator vessel located above said centrifugal pump, containing the
fluid being pumped and connected to the inlet side of said centrifugal
pump, and
a dual three-way valve operated by a common rotary shaft, the first
three-way valve being always connected to the fluid-inflow port of said
converter and alternatively connected to either the discharge port of said
centrifugal pump as a first alternative or to the higher-pressure portion
of the engine coolant circulating system as a second alternative, and the
second three-way valve being always connected to the fluid-outflow port of
said air-fluid heat exchanger and alternatively connected to either the
inlet side of said centrifugal pump as a first alternative or to the
lower-pressure portion of the engine coolant circulating system as a
second-alternative, the common rotary shaft ensuring that the both
three-way valves are positioned toward either the first alternative given
above or the second alternative given above.
whereby when said dual three-way valve is in the first alternative position
heat of vaporization is supplied only from the human-occupied compartment
and when said valve is in the second alternative position the heat of
vaporization is supplied in part from the liquid circulating within the
engine-cooling system and in part from the human-occupied compartment, in
both positions providing cooling to the compartment.
2. Apparatus as described in claim 1, further comprising:
a three-way valve permanently connected to the fluid output port of said
converter for liquid petroleum gas, having a first position directing this
fluid to said air-fluid heat exchanger and a second position directing
this fluid to the fluid-outflow port of said air-fluid heat exchanger by
means of a tee connection,
whereby said three-way valve directs the fluid from said converter through
said air-fluid heat exchanger when in the first position and bypasses said
air-fluid heat exchanger when in the second position independently of said
dual three-way valve.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
Means to supply cooled air to the cab of any apparatus having an engine
fueled by liquid petroleum gas.
2. Description of Prior Art
The prior art consists of a separate refrigeration system for air cooling,
driven by shaft horsepower extracted from the engine. This system has been
virtually universal for decades. It has been quite satisfactory until
recent environmental concerns have arisen about leakage of the refrigerant
fluid, which is virtually always fluorinated and chlorinated hydrocarbons
believed to be detrimental to creation of ozone in the upper atmosphere,
and presently scheduled to be severely restricted or banned by law in the
United States. Any refrigeration fluids which may be eligible for
substitution in such systems are likely to be much more costly, to require
considerable mechanical changes in the compressor, expansion valve,
condenser, or evaporator (expansion coil), and/or to have more severe
corrosive properties.
SUMMARY OF THE INVENTION
My invention is a combination of state-of-the-art components applicable
only to engines which are fueled by liquefied petroleum gas (LPG) of
various chemical compositions. Advantage is taken of the fact that the
liquid state of the fuel (necessary for compact ambient-temperature
storage) must be transformed into the gaseous state to achieve simple and
reliable carburetion and subsequent ignition. This change of state
requires heat to be supplied to the liquid fuel, in a converter such as a
propane converter. Although the usual practice is to obtain that heat from
the engine coolant circuit, my invention allows heat to be taken from the
passenger/driver compartment for this purpose, thus cooling the cab.
Although the amount of heat extracted from the cab is dictated by the
engine's demands instead of being selected by the human driver or
passenger (as occurs when refrigeration systems are employed), the
invention dispenses entirely with moving machinery and dynamic seals with
obvious reductions in cost and leakage. Moreover, a simple and
well-developed three-way-valve is the only moving part. The function of
this valve is to switch from extracting the heat from the cab to
extracting the heat from the engine coolant circulating system.
The physical arrangement of this invention is provision for the
conventional connection of engine coolant, from a higher-pressure point,
through the switchable dual three-way valve to the propane converter (in
the preferred embodiment), back through the dual three-way valve, and to a
lower-pressure point in the engine coolant path. Added to this is another
circuit using ethylene glycol or engine coolant and directing this fluid
from the discharge port of an electrically powered centrifugal pump,
through its own ports on the dual three-way valve to the propane
converter, out of the propane converter to the passenger compartment
heater (heat exchanger), back through the dual three-way valve, past an
air separator and into the centrifugal pump inlet. The two positions of
the shaft of the dual three-way valve determine whether the engine-coolant
circuit or the heater circuit will be supplying the heat needed in the
propane converter to vaporize and warm the propane sufficiently to prevent
icing of the converter or in the conventional engine carburetor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a typical, preferred embodiment of my
invention showing elements of the combination in perspective.
FIG. 2 is a similar view of an alternate embodiment.
DETAILED DESCRIPTION OF INVENTION
Referring to FIG. 1, functioning in the conventional way (which corresponds
to the second alternative position of dual three-way valve 9) pressurized
engine coolant tube 12 supplies hot circulating liquid, tapped from the
engine pump (not shown) which circulates liquid through the radiator heat
exchanger (no shown) to dual three-way valve 9 consisting of first
three-way valve 10 and second three-way valve 11. (These valves are
designated herein by the numeral for their always-active port.) This
stream of liquid exits three-way valve 10 and enters LPG converter 1
through heat transfer in-port 4. The stream gasifies the liquid petroleum
gas (LPG) entering converter 1 at entrance port 2, which then exits at
exit port 3, while the stream of cooled liquid exits at outflow port 5.
The effluent from exit port 3 goes to the engine, while the cooled liquid
outflow from 5 goes directly to air-fluid heat exchanger 6, entering at
fluid inlet port 7 and exiting at fluid outlet port 8. Port 8 conveys the
fluid back to the second three-way valve 11 where it is directed to the
engine coolant return line 13. Functionally, this arrangement is similar
to the prior art except that the cooled engine coolant passes through a
heat exchanger in the human-occupied passenger compartment before going
back to the engine. The heat exchanger may be the evaporator coil in a
no-longer-functional air refrigeration system, or a compartment heater,
either of which ordinarily has a fan with which the output of the air side
of the heat exchanger 6 can be monitored or controlled by the occupant.
This mode of operation of my invention supplies heat of LPG vaporization
partly from engine coolant and partly from the human-occupied compartment.
The second mode of operation (corresponding to the first alternative
position of dual three-way valve 9) occurs when the dual three-way valves
are in their first alternative position. In this case LPG converter 1
obtains the fluid entering fluid inflow port 4 through first three-way
valve 10 and centrifugal pump 14 discharge port 16. The flow path of fluid
through LPG converter 1 and air-fluid heat exchanger 6 back to the second
three-way valve 11 remains as formerly described, but on leaving three-way
valve 11 the fluid is freed of any entrapped or entrained air in
air-separator vessel 17 before entering centrifugal pump 14 at inlet port
15. As there is no source of heat for the circulating fluid other than the
air-fluid heat exchanger 6 in the human-occupied compartment, essentially
all the heat of LPG vaporization is supplied from heat exchanger 6.
Although there is no direct mixing of fluid in the two circuits described
above, in the preferred embodiment both are largely ethylene glycol with a
minimum of water admixed.
As exists with virtually every system devised by man, inputs by the various
parts of the system need to be coordinated with one another in order that
the system function as intended. This coordination is a technical matter
thoroughly familiar to those skilled in the art and unrelated to
invention. In my air cooling system, the parts needing coordination are
the temperature of the engine coolant supplied, the differential of
pressure between pressurized engine coolant tube 12 and return line 13 and
the resistance to engine coolant flow presented by the individual parts of
the coolant flow circuit, all of which affect how much engine heat reaches
the LPG in converter 1 and therefore the temperature level of engine
coolant reaching air-fluid heat exchanger 6. Whether this temperature
level is cooler than the ambient atmospheric air in the human-occupied
compartment or not also depends on ambient-air temperature. The above
remarks apply to the second alternative, when engine coolant is used. In
the second alternative the working fluid assumes whatever temperature the
balancing of heat given to the LPG and to its surroundings (including
air-fluid heat exchanger 6) permits.
It being clear that the factors discussed in the paragraph above depend
heavily on the design and the operating power level of the internal
combustion engine, as well as the characteristics of the elements combined
to constitute my invention, case-by-case application must be left to those
skilled in the art rather than attempting to discuss various applications
of my invention here. Only one possibility needs further discussion; the
possible instance in which the temperature of engine coolant to the
air-fluid heat exchanger becomes temporarily high, resulting in heating
rather than cooling the human-occupied compartment on a regular basis when
the dual three-way valve is set to the second alternative position (set
for less-than-maximum cooling). In this specific case the preferred
embodiment is depicted in FIG. 2.
FIG. 2 differs from FIG. 1 only in provision for a third three-way valve 20
at the point where fluid enters air-fluid heat exchanger 6. This is an
alternate embodiment of my invention as might be desired should the
vehicle or application be such that exclusion of engine heat from the
human-occupied compartment is for some reason (or on some occasions)
desired. Third three-way valve 20 has two positions, a first position in
which the fluid coming from LPG converter 1 is allowed to pass through
air-fluid heat exchanger 6, entering fluid inlet port 7 and leaving fluid
outlet port 8, and a second position in which fluid inlet port 7 is
blocked, and the fluid coming from LPG converter 1 passes directly into
the outlet tube (an extension of fluid outlet port 8). In the figure, the
fluid path in the first position is from line 5 to line 21 out line 22 to
inlet port 7 and from outlet port 8 to dual three-way valve's line 11. In
the second position, fluid flow is from line 5 to line 21 of three way
valve 20, out line 19 and into dual three-way valves line 11, (line 22
being a dead end at valve 20) using a tee connection.
It should be noticed that, in both embodiments of my invention, when the
human-compartment heater does double duty as a heater for the compartment
as well as a cooler the fluid path as a heater is not defined in either
FIG. 1 or FIG. 2. The art for making such connections is simply not
germane to my invention. Moreover, it is well known. Also the art (whether
simple tee connections at air-fluid heat exchanger 6 or incorporating
shutoff on three-way valves) varies from installation to installation as a
design choice of those skilled in the conventional art. These remarks
obviously do not apply when air-fluid heat exchanger 6 is separate from
the human compartment heater.
My invention having been described in preferred embodiments, it is clear
that those skilled in the art can make modifications without use of the
inventive faculty. Therefore, the scope of the invention is to be regarded
as the scope of the following claims:
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